program DistPointPlane;

{$APPTYPE CONSOLE}
var
xo, yo, zo : real;
x1, y1, z1, x2, y2, z2, x3, y3, z3 : real;
dist : real;
a, b, c, d: real;
factor : real;
begin
  readln(x1, y1, z1);
  readln(x2, y2, z2);
  readln(x3, y3, z3);
  readln(xo, yo, zo);
  a := (y1-y2)*(z2-z3)-(y2-y3)*(z1-z2);
  b := -((x1-x2)*(y2-y3)-(x2-x3)*(z1-z2));
  c := (x1-x2)*(y2-y3)-(x2-x3)*(y1-y2);
  d := -(a*x1+b*y1+c*z1);
  factor := a*a+b*b+c*c;
  if (factor=0) then begin writeln('This plane is not able to be');end else
  begin
    dist := (a*xo+b*yo+c*zo+d)/(sqrt(a*a+b*b+c*c));
    writeln(abs(d):0:3);
  end;
  readln;
end.
 